Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy from wind using known airfoil principles and transmit the kinetic energy through rotational energy to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
To ensure that wind power remains a viable energy source, efforts have been made to increase energy output by modifying the size, configuration and capacity of wind turbines. One such modification has been to include a wingtip device, such as a winglet, at the tip of each wind turbine rotor blade. Generally, winglets can be employed to improve the overall efficiency and performance of a wind turbine. For example, a winglet may decrease the amount of spanwise flow generated at the tip of a rotor blade and, thereby, reduce induced drag on the rotor blade. Winglets may also be installed on rotor blades to reduce the overall diameter of the wind turbine so that loads can be minimized, and to reduce noise emitted by the blades. Further, winglets may also provide an increase in the power coefficient of a wind turbine and, thus, reduce the cost of energy generated by the wind turbine.
However, conventional winglets may have a variety of disadvantages. For example, conventional winglets are generally attached to rotor blades such that the winglets and rotor blades form sharp corners therebetween. These abrupt corners may, for example, increase the drag at the intersections between the winglets and rotor blades, and may thus diminish the benefits, such as increased performance, that were anticipated from the use of the winglets. Further, conventionally known blended winglets, while purportedly reducing the drag at the winglet-rotor blade intersection, may provide only minimal performance benefits.
Thus, an improved winglet for use with a rotor blade in a wind turbine would be desired. For example, a winglet that reduces the drag at the winglet-rotor blade intersection while increasing the performance of the rotor blade would be advantageous.